


Prove It

by Skylark_Stardust



Category: Fire Emblem: Fuukasetsugetsu | Fire Emblem: Three Houses
Genre: Anal Fingering, Anal Sex, Blow Jobs, Doggy Style, Drunk Sex, F/M, Oral Sex, POV First Person, Porn, Porn with Feelings, Rough Sex, Sex, Vaginal Fingering, Vaginal Sex
Language: English
Status: Completed
Published: 2020-01-07
Updated: 2020-01-07
Packaged: 2021-02-27 16:02:18
Rating: Explicit
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 4,806
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/22159801
Author URL: https://archiveofourown.org/users/Skylark_Stardust/pseuds/Skylark_Stardust
Summary: Byleth wants to know the real Sylvain... or maybe just one night with him.  She can't decide.
Relationships: Sylvain Jose Gautier/My Unit | Byleth
Comments: 1
Kudos: 53





	Prove It

**Author's Note:**

> This is my first time posting so please be kind.
> 
> If you're underage, don't read this. Sex isn't really like this... well, at least not always.

I swear I hadn’t planned it but to say “it just happened” wouldn’t be entirely honest either. I was having dinner with Manuela and Shamir. It had been a long week and I was looking forward to blowing off steam over dinner and mead. We had been in the dining hall for a while, laughing and enjoying each other's company as well as several glasses of beverages. Manuela had filled us in on the latest drama in her relationship with a knight twice her age and unfortunately Shamir had been increasingly curious about my own dating scene.Before coming to the monastery I’d been screwing another mercenary. He was the exemplary "nice guy" and I stuck with it hoping it would get more exciting. Conversation with him was mediocre, much like the sex but I felt like I should be interested in him so I’d just stuck with it. Leaving the mercenaries was a relief. Even my sexless life at Garreg Mach was more exciting than sex with him.

They knew my sexual interests weren't always vanilla and laughed as I described how excited he'd been when I'd suggested doggy style. Like it wasn't a given that I liked to be fucked from behind while someone was smacking my ass and pulling my hair. The conversation was getting a bit unruly when I saw him looking at me.

My heart skipped a beat as our eyes met. I felt heat in my loins instantly and looked away quickly. Reaching for my glass, I took a long drink feeling the warmth of the alcohol as it ran down my throat. Glancing back in his direction, I noticed he’d looked away, talking to Felix—probably teasing him about his commitment to training rather than chasing women.

From the moment I’d arrived at the monastery he had been trying hard, some might say too hard, and that was exactly why I had refused to hook up with him. He drove me nuts with his stupid fucking persona that he thought he had to show the world. I knew he was more than whatever damage made him act that way. Still, he’d yet to let his guard down and fuck if I was going to encourage it. At least that’s what I’d told myself for the first few months I’d been at Garreg Mach.

It had all started after class one day when he’d stuck around and snuck me a note. He was gorgeous and exactly my type. His auburn hair was constantly disheveled and tall frame and wide shoulders teased the body that was underneath. He was well read and intelligent and one of the strongest fighters we had. The only problem was that I knew for a fact that he couldn’t keep it in his pants.  
Don't get me wrong, I love sex. I even love kinky sex. However, I was his professor. I'd done the sleeping around thing as a mercenary and I wasn’t into sharing. I was a one guy kind of girl and kind of wanted the same thing in return, nothing serious but monogamous while also involving crazy fucking.

Nevertheless I read his note and found myself responding regardless. His was full of flowery words, my perfection, the things he would do for me, all of the things I was certain he told every other woman he tried to “court.” Everything was perfectly honorable as any letter from a noble was expected to be. So I wrote him back and I explained that wasn't what I was looking for. I was his professor but more importantly I was as dumb enough to fall for his lines. I knew his game and while he may not have realized, I’d been watching his behavior with other women. I told him if he wanted anything from me at all, then he’d have to show me his real self. I truly doubted he’d be able to but still we secretly continued to exchange letters and I found myself strangely drawn to him.

So we’d become friends. I was his professor but we were the same age and it was hard not to fall into a friendship. Sometimes I’d spar with Felix and magically he’d turn up to train with us, as if he was there of his own accord, giving up flirting and chasing women for the afternoon. He told me about his dating escapades, both the successes and the failures, and when the successes inevitably turned into failures. I told him he was a jerk who needed to learn how to treat women. He’d always tell me, that if I’d let him, he’d forsake all other women and treat me right, in every way I could imagine. I’d remind him that he used that line on every other woman who knew his reputation and it wouldn’t work on me. He’d feign being hurt but something in his eyes told me he wasn’t as unaffected as his smirk would suggest.

We wrote notes for week, passing them after class. The more we wrote the more intimate they became. He had told me about his crest, his parents, his brother, the reasons why he was angry with the women who used him for his crest and the reasons he played the games he did. I told him about my life before Garreg Mach, not knowing who my mother was, missing Jeralt with all of my heart despite the secrets he kept, and what life was like as a mercenary.

He asked me questions about that life, about fighting and traveling, about being on the road, one of few women amongst a company of men. I’d grown up quickly, in more ways than one, and while I didn’t hide that from him, I didn’t give him details. Yet once he knew I’d laid with a man, more than one actually, he couldn’t seem to let that drop. He teased me about giving him some, but would always then back track to make sure I knew he wasn't pressuring me into anything. He turned me on.

It didn’t take long before his mere presence would turn me on. His furtive looks during class, his body during training, the words he’d write. They’d all have the same effect on me. I would be lecturing or sitting at my desk, around any number of students and suddenly I'd feel my panties getting soaked. He made me smile and made me laugh and most of all he made me horny as hell.

It had taken weeks but I began entertaining the idea. What would it hurt to fuck this incredibly sexy man? We would have a good time, maybe more than one...and we both knew it was just fucking. I wouldn’t get attached and he’d move on to his next conquest after he’d had his fill. So as we continued writing, we started sharing our favorite sexual exploits with one another.

He explained how hot it felt to him when secret and discreet. He said he liked sneaking around. He also talked about how making someone he didn't even know lose control and hearing them cum was the biggest turn on he had. I told him about how much I like to be manhandled and that I love rough sex. I told him I loved ass play and it got me off more than anything.

Now I had him, He said he'd never been with a woman who enjoyed anal. I explained that I'd found my love for it while on the road with the mercenaries. There were times of the month when I was bleeding too heavily and my ass was definitely preferable. Then there were the times that I wanted to fuck but couldn’t risk pregnancy. It had started for practicality but turned into some kind of fetish. I like that it was taboo, that it hurt in just the right way, and that there was nothing that made me feel more full. I started receiving notes explaining all of the things he wanted to do to my ass. And I responded with nothing but encouragement.

The last couple weeks I'd spent talking to him had me constantly wet. My pussy was constantly in need and I masturbated more times than I could count. He would write me naughty things asking me to touch myself while I read them and then wanting me to writer him back all about what I’d done and how I'd cum.

I'd lean over his desk, giving him a view my top. When we trained, I’d be sure to touch him whenever I could, correcting his stance when there wasn’t a damn thing wrong with it. And when we sparred I'd press my body against his. More than once I thought Felix or Dimitri had found us out but if they did, they were discrete enough not to point it out.

He had told me that we could spend time together, alone, anytime I wanted. He didn't push. And I kept wavering. Was it a good idea to fuck a student, especially the one student that would tire of me and move on. We’d been writing and flirting for weeks and I liked it. I said I wouldn’t get attached but I liked this feeling of being desired by him. Would fucking him be worth losing his attention and this feeling that was becoming so addictive?

And in the past few days I'd come to realize that he’d given me what I’d asked. While in class and training, pretty much any time I saw him, he still wore his mask. He still played nonchalant, more into games and fun and women than any of the work we were doing and never outright acknowledging the seriousness of our battles. Yet he’d shown vulnerability in his letters, and not simply the vulnerability that came with sharing about intimate sexual experiences. He’d told me about his family and his life before Garreg Mach as well as his hopes and dreams for the future.

I rarely let us have time alone, knowing the outcome if and when we did but I realized that in battle I always saw the real him. I always kept him close, not because he couldn’t take care of himself and his soldiers but for the opposite. He was strong and he was a brilliant tactician. If the tides of battle started to shift, he didn’t have trouble changing strategies with it. And truly, if I wanted anyone to have my back, it was him. I trusted him and in those battles I saw his walls fall. It was hard to wear a persona when you were fighting for your life. I saw his genuine joy that came with triumphs as well as the true grief when he lost any of his soldiers. And in this realization, I had to remind myself again that the plan was not to fall for this womanizer who had no qualms throwing women away.

So here I was, drinking with my friends and feeling nervous and unsure with him just across the room. The more I drank the hornier I got and the more I wanted him. I finally met his eyes, staring into them and trying to communicate everything I was thinking in that one look. Then I downed my drink before getting up and giving my excuses to Manuela and Shamir, telling them it was time for me to get my drunk ass to bed, which wasn’t entirely a lie.

I had just arrived back to my personal quarters and was scrambling to pick up when there was a light knock at the door. My heart sped up as the nerves kicked in. He’d known what that look meant—of course he had. I had just a moment to wonder what the hell I was doing as I walked to the door. Opening it I felt unsure, I didn't want to have second thoughts but I was. He was standing there in his black uniform, tall frame silhouetted by the darkness. One hand was on the back of his neck and his look was tentative, almost bashful and questioning. It was like he knew how uncomfortable I was feeling. I know I blushed, feeling suddenly shy.

He stepped forward, shutting the door behind him. I felt his hands slide across my hips and encircle me as he pulled me tight against him. He whispered in my ear, "you're beautiful." Then I felt his hand slide up to my neck, squeezing slightly as he pulled my mouth toward his. I had told him I liked to feel a man's hands around my neck during sex. Just knowing I'm vulnerable makes me hot as hell. I moaned into his mouth as I felt his tongue slide into mine. He kissed me hard as I felt my back slam against the wall.  
He bit my lip hard before moving his hand down my body so that his mouth could go to work on my neck. His mouth and tongue and teeth grazed my neck as my pulse raced. I felt his teeth nip at my ear and my pussy throbbed as I rubbed against him. My hands slid over his stomach and around him as I grabbed his belt and pulled him hard against me. I moaned even louder as his hands squeezed my tits, finding my nipples through the material of my top.

He pulled back looking at my face as he squeezed hard. I screamed out at the pain in my nipples as I watched him smile. I bit my lip panting and breathing hard. I felt him pulling up the hem of my top before he grabbed it, pulling it over my head and throwing it aside. He spun me around and I put my hands up just in time before he rammed me face first into the wall. His hands were all over my ass as I felt his tongue lick slowly down my spine. Reaching up he unhooked my bra and slide it down my shoulders.  
He pressed his body firmly against mine as his hand went back to my throat. I could feel the rough fabric of his pants as his hard dick pressed against my ass through it. His other hand slid down my body snaking its way into my shorts and under my panties. My pussy was already soaked and I almost screamed as his fingers danced across my clit. He held my throat tightly with his mouth hot on my neck as I felt his fingers slide inside me.

My hands reached behind me. Grabbing his hips and his legs, trying to hold onto anything to keep me grounded as my body trembled against him. I could feel my orgasm building and knew I was getting close. My pussy clenched his fingers as he drove them into me harder and harder. Making me crazy. He turned me around almost instantly, holding me tightly against the wall by the throat my eyes meeting his as he finger fucked me. Just the sight of him made me lose control and I screamed and bucked against his hand as I lost control. My pussy leaking its juices into his palm.

He smirked, pulling his hand away. I watched as his tongue flicked over his fingers, tasting me, before he held it out. I opened my own mouth, sucking hard on his fingers. As I tasted my pussy on him, I felt myself already beginning to want him back inside me. I reached my hand toward his cock, wanting to give him even half the pleasure he had just given me. He pushed me down until I was kneeling in front of him. I was still wearing my shorts, tights and soaking wet panties while he was completely dressed.

I leaned forward, kissing his hard cock through the fabric of his pants. Then sliding my tongue over his zipper. Reaching up I careful undid his pants and slid the zipper down. Reaching inside I pulled out his hard cock. I wanted it so fucking bad. Looking up at him I slid my tongue over the tip, tasting him. I watched his face as I continued lightly teasing him with my tongue. Running it ever so lightly around the head and down the shaft. I went to work, teasing and tasting until he finally grabbed my hair.

I opened my mouth wide as he shoved his dick in as far as it would go. I gagged as it hit the back of my throat making my eyes water. I went to work, moving my head up and down as his fingers tangled in my hair. Swirling my tongue around and around as my mouth moved up and down his cock sucking him in. My hands gripped his ass, trying to pull him in and take him as far into my throat as I could. I looked up at him even as my eyes watered. I wanted him inside me, filling me, in any and every place he wanted.

He pulled out, grabbing his dick and slapping it against my lips. I opened my mouth, sticking out my tongue. I felt him slapping it. Spit covering my face and sliding down my tits. I felt my pussy quiver. Reaching forward, I rubbed his balls lightly before moving my hand to his cock and stroking. I flicked my tongue over his balls, licking, kissing and sucking while I stroked him. Sucking one then the other into my mouth.

I moved my mouth back to his cock, slowly taking it all the way inside. Watching his face as he looked down at me and enjoying as he watched his dick disappear. I gagged but kept moving, taking it all the way in before pulling away and beginning to move up and down as fast as I could. I wanted to taste him. I wanted his cum in my mouth, filling it up. I don't particularly like the taste of cum, but I wanted his. At that moment, I wanted anything he would give me. Suddenly he grabbed my hair, pushing my head all the way down his shaft as he started squirting in my mouth.

Warm salty liquid hit my throat, gagging me but it kept coming filling up my mouth. I tried to swallow as much as I could but some dribbled down my chin. He slid out of me and I reached up, wiping my chin and licking his cum off my fingers. He reached down, helping me up and held me close to him as he kissed me hard. His fingers pressing hard into my ass as I felt his wet cock against my stomach. I felt his fingers slip under my shorts and he bent over to slide them down my legs, along with my tights and underwear. I stepped out of them and he stood up, holding my panties in his hand.

"Open." He said, looking at my mouth. I opened my mouth as he slid my soaking wet panting into it, gagging me. Moving to the chair, he bent me over the back so that my ass was sticking up high and I was face down against the cushion. With that he started spanking me. He knew I liked spankings. I had told him that I liked having my ass bruised the next day as a reminder of what I'd done the night before. So that every time I move there's just enough pain to bring back the memories, to make my pussy clench and get wet all over again.

He spanked one cheek and then the other, my cries muffled by the panties in my mouth. The sound of his hand cracked against my skin and I could feel my ass heating up. He slid his hand down to my pussy and I could hear him chuckle as he felt how wet I was. Juices from my pussy were running down my thighs. His hands left me and I felt momentarily lost without them, then I felt his tongue slide up my thigh licking the juices from my pussy. He moaned when he tasted it and it took everything in me not to try to move so that his mouth was on my slit.

Slowly he moved his tongue up one thigh, then the other. He flicked lightly over the lips of my pussy. Teasing me as pay back for teasing him. If my mouth hadn't been full of my panties, I would have been begging him. Cool air hit my clit as he blew on it then wrapped his lips around it. He kissed and licked it, circling it with his tongue. His hands held my hips firmly in place as he drove me wild. I felt his tongue slide up and down my slit, flicking my clit each time then moving away.

He slid his tongue from my clit down my slit and dipped inside me. I screamed, feeling like something inside was going to break open. He ran his tongue around my opening then inside, fucking me with it. I tried to move, but he held me immobile, making me crazy. I felt his tongue leave my pussy and move further back, rimming my asshole as his fingers moved to my clit. I was screaming and panting and moaning. He knew I liked ass play, and I knew he didn't get a lot of it. He seemed intent on making sure he got some in tonight.

He slid his tongue in my ass over and over, getting it nice and wet then I felt his finger rubbing against it. I relaxed as his mouth moved back to my pussy. I started to cum again as his finger slid inside my tight asshole. I came so fucking hard, squirting all over him as his tongue lapped up all it could and his finger fucked my ass.

>  
I was spent, coming down after that. I felt him move me so that I was laying on my back with my legs spread on the bed. I watched, barely able to move, as he positioned his cock at the entrance to my pussy. He reached up, grabbing my throat with both hands and moving his face until just over mine. Staring into my eyes, he rammed inside me as hard as he could. I screamed loudly as his cock stretched my tight pussy. My eyes didn't leave his, even though they were watering. He leaned forward, removing the panties from my mouth and kissing me hard as he began to fuck me harder. My legs wrapped around him, pulling him in as hard as I could. My arms reached up, wrapping around him as well, pulling him toward me.

My mouth was all over him, kissing him, licking him, biting him. I wanted all of him. I wanted to taste him and touch him and fuck him until there was nothing left. Regaining my strength, I began to move, rolling us over. I wanted to be on top. Feeling me move, he rolled us over, never breaking pace. I rode him as hard as I could, grinding against him, feeling him fill me up. His mouth closed over my right nipple, licking and sucking. He bit hard and I screamed but pulled his hair so his head was closer, taking more of my tit in his mouth.

I felt his fingers sliding down the cleft of my ass. He reached his hand around sticking his fingers in my mouth. I licked and sucked them, getting them nice and wet, then I felt him slide them over my asshole pressing lightly. His cock was making my pussy so full and I felt his fingers slide into my ass. I felt more full than I ever had. I felt myself about to cum again and grinded hard against him. I came again, biting into his shoulder, my fingernails leaving little half moons in his skin. He just kept fucking my pussy.

When I stopped shaking, he moved me off of him. Standing me up, he put me over the back of the chair again. He bent me over and I happily displayed my ass for him. I felt his saliva slide over my hole and his fingers begin to work it in. The head of his cock pressed slowly against my ass. I could feel it stretching tightly as he began to push inside. The stretching hurt, but I liked it. He reached around, rubbing my clit as he slowly inched his way in.

Enjoying the feeling of being stretched, I pushed back against him. I heard him gasp as his dick sank all the way into my ass. He stayed liked that, with his dick buried inside and his hands running all over my back and ass. I loved every second of it. I wanted to stay like that forever. He reached forward, grabbing my hair and pulling me up by it. Wrapping his hand back around my throat, he began moving in and out of my ass. Encouraging him, I moved my hips back and forth, quickening the speed. He rammed hard into me, over and over.

I reached back, grabbing his hips, encouraging him. His hand tightened around my throat and I felt his speed increase. I knew he was close. I tightened my ass around him as hard as I could and begged “Please Sylvain, cum in my ass!” He yelled out then bit into my shoulder as I felt my ass filling up with his hot cum. I loved the way it felt to have cum inside me.

He waited a moment before he pulled out of me. I don’t think either of us were eager for the separation. The his arms wrapped around me and I let out a squeal as he picked me up landing us both on the bed in a tangle of limbs. I smiled up at him, running my fingers through his hair which was even more rumpled than it normally was. He kissed my forehead, my cheeks, my nose, ending with my mouth. Pulling back he said, “you’re so fucking perfect.”

Suddenly my languid body tensed. Panic was seizing my heart but I didn’t want to ruin the moment, I wanted to be able to enjoy every moment of this. I’d signed up for the fucking but I hadn’t thought about the cuddling afterward and now knowing that there was an expiration date on our time together I found myself feeling sad already. He leaned back, looking at me with concern on his face. “By, what’s wrong?” he asked tucking a stray strand of hair behind my ear.

I looked away, his beauty was overwhelming sometimes. He whispered, “Byleth, look at me.” I moved my eyes back to him. He reached forward, tracing his fingers along my cheekbone. “It wasn’t a line, I really do think you’re perfect, and it isn’t just because that was the best fucking sex of my life. You’re beautiful, so intelligent, funny, and you care so much about all of the people here. I know you think I say this to all of the women I’m with but I don’t, I’m usually out the door by now. You taught me that my crest doesn’t have to control me and I’m tired of assuming that every single woman is only interested in me because of it. I’m tired of believing that my crest is all I’m worth. You showed me that I’m more than that. I like who I am when I’m with you. I want to be with you and only you, for as long as you’ll have me.”

I touched his face, searching his eyes because even though he was saying all of the right things, there was still a part of me that wasn’t sure if he was just saying the things I wanted to hear. I’d heard him say so many things to different women and rationalize it later. He looked at me in all earnestness, no hint of his trademark smirk and asked “don't you trust me?” I didn’t want to hurt him or even disappoint him but I also couldn’t lie. “I’m sorry, I want to. I trust you with my life but I can’t, not this.”

He looked at me briefly with sad eyes then he put his head in his hands but only for a moment. When he looked up at me he was smiling, genuinely. “Well I can't say that I blame you. I guess this is what I deserve. I’m just going to have to prove it to you and I’m sure as hell going to have fun doing it.” Then his mouth was on mine again, and again, and again.


End file.
